Why does INCREASING the outdoor temperatures on my cooling design days REDUCE my PTAC cooling coil autosized capacities?

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Two identical models, only difference is the SizingPeriod:DesignDay objects for heating design day, "Maximum Dry-Bulb Temperature" and "Wetbulb or DewPoint at Maximum DryBulb." In one model I've hard-inputted these cooling sizing temperatures to be about 4degC higher to approximate a 2050 climate scenario.

In the model with higher dry- and wet-bulb temperatures for my cooling design days, the HVACTemplate:Zone:PTAC cooling coils autosized to LOWER capacities by about 4%. That is, the autosized "Cooling Coil Gross Rated Total Capacity {W}."

This certainly goes against intuition... does the model take into account other factors when autosizing PTAC cooling coils? What am I missing?

Model 1 cooling design day:

SizingPeriod:DesignDay,
Boston Logan IntL Arpt Ann Clg .4% Condns DB=>MWB,  !- Name
7,                       !- Month
21,                      !- Day of Month
SummerDesignDay,         !- Day Type
32.7,                    !- Maximum Dry-Bulb Temperature {C}
8.4,                     !- Daily Dry-Bulb Temperature Range {deltaC}
,                        !- Dry-Bulb Temperature Range Modifier Type
,                        !- Dry-Bulb Temperature Range Modifier Day Schedule Name
Wetbulb,                 !- Humidity Condition Type
22.9,                    !- Wetbulb or DewPoint at Maximum Dry-Bulb {C}
,                        !- Humidity Condition Day Schedule Name
,                        !- Humidity Ratio at Maximum Dry-Bulb {kgWater/kgDryAir}
,                        !- Enthalpy at Maximum Dry-Bulb {J/kg}
,                        !- Daily Wet-Bulb Temperature Range {deltaC}
101253,                  !- Barometric Pressure {Pa}
6.3,                     !- Wind Speed {m/s}
270,                     !- Wind Direction {deg}
No,                      !- Rain Indicator
No,                      !- Snow Indicator
No,                      !- Daylight Saving Time Indicator
ASHRAEClearSky,          !- Solar Model Indicator
,                        !- Beam Solar Day Schedule Name
,                        !- Diffuse Solar Day Schedule Name
,                        !- ASHRAE Clear Sky Optical Depth for Beam Irradiance (taub) {dimensionless}
,                        !- ASHRAE Clear Sky Optical Depth for Diffuse Irradiance (taud) {dimensionless}
1;                       !- Sky Clearness

Model 2 cooling design day:

SizingPeriod:DesignDay,
Boston Logan IntL Arpt Ann Clg .4% Condns DB=>MWB,  !- Name
7,                       !- Month
21,                      !- Day of Month
SummerDesignDay,         !- Day Type
36.63,                   !- Maximum Dry-Bulb Temperature {C}
8.4,                     !- Daily Dry-Bulb Temperature Range {deltaC}
,                        !- Dry-Bulb Temperature Range Modifier Type
,                        !- Dry-Bulb Temperature Range Modifier Day Schedule Name
Wetbulb,                 !- Humidity Condition Type
26.12,                   !- Wetbulb or DewPoint at Maximum Dry-Bulb {C}
,                        !- Humidity Condition Day Schedule Name
,                        !- Humidity Ratio at Maximum Dry-Bulb {kgWater/kgDryAir}
,                        !- Enthalpy at Maximum Dry-Bulb {J/kg}
,                        !- Daily Wet-Bulb Temperature Range {deltaC}
101253,                  !- Barometric Pressure {Pa}
6.3,                     !- Wind Speed {m/s}
270,                     !- Wind Direction {deg}
No,                      !- Rain Indicator
No,                      !- Snow Indicator
No,                      !- Daylight Saving Time Indicator
ASHRAEClearSky,          !- Solar Model Indicator
,                        !- Beam Solar Day Schedule Name
,                        !- Diffuse Solar Day Schedule Name
,                        !- ASHRAE Clear Sky Optical Depth for Beam Irradiance (taub) {dimensionless}
,                        !- ASHRAE Clear Sky Optical Depth for Diffuse Irradiance (taud) {dimensionless}
1;                       !- Sky Clearness

Both models are set for system sizing:

SimulationControl,
Yes,                     !- Do Zone Sizing Calculation
Yes,                     !- Do System Sizing Calculation
Yes,                     !- Do Plant Sizing Calculation
Yes,                     !- Run Simulation for Sizing Periods
Yes,                     !- Run Simulation for Weather File Run Periods
Yes;                     !- Do HVAC Sizing Simulation for Sizing Periods

Thanks all!